Knowledge Base

How to reproject the IMS 1km or 4 km GeoTIFFs to geographic latitude/longitude

If you need to reproject the IMS 1 km or 4 km GeoTIFFs to geographic latitude/longitude, we recommend using the Geospatial Data Abstraction Library (GDAL). Instructions for downloading and installing it can be found here:

https://gdal.org/download.html

Below are instructions for using GDAL directly in the command line or in a python script.

Command Line

  1. Open a terminal and navigate to the folder where the GeoTIFFs you want to reproject are located.
  2. Issue the following command to reproject and save the output as a new GeoTIFF:
     

    gdal_warp -t_srs EPSG:4326 -te -180 -90 180 90 -srcnodata 0 -r near -of GTiff -co COMPRESS=deflate -wo NUM_THREADS=4 <input GeoTIFF> <output GeoTIFF>

    For example, if you wanted to reproject the 1 km GeoTIFF 'ims_2020335_1km_GIS_v1.3.tif' and save it as 'out.tif':
     

    gdal_warp -t_srs EPSG:4326 -te -180 -90 180 90 -srcnodata 0 -r near -of GTiff -co COMPRESS=deflate -wo NUM_THREADS=4 ims2020335_1km_GIS_v1.3.tif out.tif

Python

Below is some example python code for reprojecting a 1km GeoTIFF:

from osgeo import gdal

input_file = 'ims_2020335_1km_GIS_v1.3.tif'
output_file = 'out.tif'

gdal.Warp(output_file, input_file,
          options='-t_srs EPSG:4326 '
                  '-te -180 -90 180 90 '
                  '-srcnodata {} '.format(0) +
                  '-r near '
                  '-of GTiff '
                  '-co COMPRESS=deflate '
                  '-wo NUM_THREADS=4')